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United States Patent |
5,665,019
|
Sheffer
,   et al.
|
September 9, 1997
|
Chain guide mounting assembly for the reduction of chain induced noise
and vibration in a chain driven overhead cam internal combustion engine
Abstract
A chain guide mounting assembly for reducing chain related noise in a chain
driven overhead cam internal combustion engine. The assembly includes
vibration isolation means for mounting the chain guide to the engine.
Resilient members, fitted within the chain guide, provide the vibration
isolation, which, in turn, reduces undesirable chain noise. To prevent
undue lateral movement of the chain guide member as a result of the chain
force exerted thereon, a rigid sleeve in interference engagement is fitted
within bores of the resilient members. As a result, a preload is provided
on the resilient members so as to reduce the amount of undesirable lateral
movement.
Inventors:
|
Sheffer; Eric J. (Highland, MI);
Osborne; William H. (Southfield, MI);
Nowicki; Wayne A. (Ypsilanti, MI)
|
Assignee:
|
Ford Global Technologies, Inc. (Dearborn, MI)
|
Appl. No.:
|
598832 |
Filed:
|
February 5, 1996 |
Current U.S. Class: |
474/111; 474/140; 474/148; 474/150 |
Intern'l Class: |
F16H 007/08; F16H 007/00; F16H 007/18; F16H 007/24 |
Field of Search: |
474/96,111,140,148,150,273,902
226/196,198
|
References Cited
U.S. Patent Documents
2613544 | Oct., 1952 | Cullman.
| |
3128999 | Apr., 1964 | Schmitt.
| |
3180594 | Apr., 1965 | Connell.
| |
3322377 | May., 1967 | Morlon.
| |
3482808 | Dec., 1969 | Rofe et al.
| |
3728793 | Apr., 1973 | Makinson et al.
| |
3845827 | Nov., 1974 | Schulin.
| |
3868190 | Feb., 1975 | Moore | 403/189.
|
3972119 | Aug., 1976 | Bailey.
| |
4049308 | Sep., 1977 | Martin.
| |
4069719 | Jan., 1978 | Cancilla.
| |
4480603 | Nov., 1984 | Tsuboi | 123/90.
|
4480608 | Nov., 1984 | Valev.
| |
4670985 | Jun., 1987 | Biersteker | 30/381.
|
5058867 | Oct., 1991 | Hadano et al.
| |
5445365 | Aug., 1995 | Forderer.
| |
Primary Examiner: Graysay; Tamara L.
Assistant Examiner: Hartmann; Gary S.
Attorney, Agent or Firm: Ferraro; Neil P.
Claims
We claim:
1. A chain guide mounting assembly for an internal combustion engine having
a crankshaft, a camshaft, and a chain connecting said crankshaft to said
camshaft, said assembly comprising:
an elongate chain guide member fastened to said engine by vibration
isolation means, said chain guide member having a first end with a first
bore formed therein and a second end, opposite said first end, with a
second bore formed therein and a chain guide surface for guiding said
chain, with said first and second bores receiving first and second
vibration isolation means, respectively, with each said vibration
isolation means comprising:
a first, substantially cylindrical resilient member having an exterior side
wall, an axial bore therethrough and a flange portion at one end thereof
fitted within one of said bores formed in said chain guide member such
that an underside surface of said flange portion rests on a first outer
surface of said chain guide member;
a second, substantially cylindrical resilient member having an exterior
side wall, an axial bore therethrough and a flange portion at one end
thereof fitted within said one of said bores formed in said chain guide
member such that an underside surface of said flange portion rests on a
second outer surface of said chain guide member;
a rigid, substantially cylindrical sleeve in interference engagement within
said bores of said first and said second resilient members such that a
radial preload is applied to said first and second resilient members; and,
a fastener passing through said sleeve and said bores for fastening said
chain guide member to said engine.
2. A chain guide mounting assembly according to claim 1 further comprising
a chain tensioning device for applying tension on said chain to reduce
chain slack therein.
3. A chain guide mounting assembly according to claim 2 wherein said chain
tensioning device comprises:
an elongate chain tensioning member having a first end, a second end
opposite said first end and a chain support surface intermediate said
first and second ends for supporting said chain, said first end being
pivotally connected to said engine; and,
a force application means engaging said second end such that when a force
is applied by said force application means, said chain tensioning member
pivots about said first end thereby applying a lateral force at said chain
support surface on said chain that serves to reduce slack in said chain.
4. A chain guide mounting assembly according to claim 3 wherein an elongate
resilient member is mounted to said chain support surface.
5. A chain guide mounting assembly according to claim 1 further comprising
a washer overlaying a top surface of said flange portion of said second
resilient member.
6. A chain guide mounting assembly according to claim 1 wherein said first
and second resilient members each comprise a material selected from the
group consisting of a fluorinated hydrocarbon and a fluorosilicone.
7. A chain guide mounting assembly according to claim 1 wherein an elongate
resilient member is mounted to said chain guide surface.
8. A chain guide mounting assembly according to claim 1 wherein said sleeve
has an axial length less than the length of said first and second
resilient members when fitted within said one of said bores formed in said
chain guide member such that an axial preload is applied to said first and
second resilient members when said chain guide member is mounted to said
engine.
9. A chain guide mounting assembly according to claim 1 wherein said sleeve
comprises a flanged portion at one end thereof for bearing against the
engine.
10. A chain guide mounting assembly according to claim 9 wherein said first
resilient member has an annular recess about said bore at said flange
portion end for receiving said flange portion of said sleeve.
11. A chain guide mounting assembly according to claim 10 wherein said
flange portion of said sleeve is a frusto-conical flange and said annular
recess about said bore is a frusto-conical recess.
12. A chain guide mounting assembly according to claim 1 wherein said first
resilient member comprises an annular recess in an underside surface of
said flange portion of said first resilient member near a boundary between
said flange portion and said exterior side wall.
13. A chain guide mounting assembly according to claim 1 wherein said
second resilient member comprises an annular recess in an underside
surface of said flange portion of said first resilient member near a
boundary between said flange portion and said exterior side wall.
14. A chain guide mounting assembly for an internal combustion engine
having a crankshaft, an overhead camshaft, and a chain connecting said
crankshaft to said camshaft, said assembly comprising:
a chain tensioning device for applying tension on said chain to reduce
chain slack therein, said device comprising:
an elongate chain tensioning member having a first end, a second end
opposite said first end and a chain support surface intermediate said
first and second ends and having an elongate resilient member mounted on
said chain support surface for supporting said chain, said first end being
pivotal connected to said engine; and,
a force application means engaging said second end such that when a force
is applied by said force application means, said chain tensioning member
pivots about said first end thereby applying a lateral force at said chain
support surface on said chain that serves to reduce slack in said chain;
an elongate chain guide member fastened to said engine by vibration
isolation means, said chain guide member having a first end with a first
bore for receiving a first vibration isolation means, a second end,
opposite said first end, with a second bore for receiving a second
vibration isolation means, a chain guide surface intermediate said first
and second ends and having an elongate resilient member mounted on said
chain guide surface for guiding said chain, and further having a vibration
isolation means, with said vibration isolation means comprising:
a first, substantially cylindrical resilient member comprising:
i) an exterior side wall,
ii) an axial bore through said member,
iii) a flange portion at one end thereof, said first resilient member
fitted within said first bore of said chain guide member such that an
underside surface of said flange portion rests on a first outer surface of
said chain guide member,
iv) a frusto-conical annular recess about said bore at said flange portion
end, and
v) an annular recess in an underside surface of said flange portion near a
boundary between said flange portion and said exterior side wall;
a second, substantially cylindrical resilient member comprising:
i) an exterior side wall,
ii) an axial bore through said member,
iii) a flange portion at one end thereof, said second resilient member
fitted within said second bore of said chain guide member such that an
underside surface of said flange portion rests on a second outer surface
of said chain guide member, and,
iv) an annular recess in an underside surface of said flange portion near a
boundary between said flange portion and said exterior side wall;
a rigid, substantially cylindrical sleeve in interference engagement within
said bores of said first and said second resilient members such that a
radial preload is applied to said first and second resilient members, said
sleeve having a frusto-conical flange portion at one end thereof for
bearing against the engine, said sleeve further having an axial length
less that the length of said first and second resilient members when
fitted within said bore of said chain guide member;
a washer overlaying a top surface of said flange portion of said second
resilient member;
a fastener passing through said sleeve and said bores for fastening said
chain guide member to said engine such that an axial preload is applied to
said first and second resilient members when said chain guide member is
mounted to said engine; and,
wherein said first and second resilient members each comprise a material
selected from the group consisting of a fluorinated hydrocarbon and a
fluorosilicone.
15. A method of mounting a chain guide member to an internal combustion
engine having a crankshaft, an overhead camshaft, and a chain connecting
said crankshaft to said camshaft, said method comprising the steps of:
forming a chain guide member with a chain guide surface for guiding said
chain;
fastening said chain guide member to said engine using vibration isolation
means comprising the steps of:
fitting a first, substantially cylindrical, resilient member having an
exterior side wall, an axial bore therethrough and a flange portion at one
end thereof within a bore formed in said chain guide member such that an
underside surface of said flange portion rests on a first outer surface of
said chain guide member;
fitting a second, substantially cylindrical, resilient member having an
exterior side wall, an axial bore therethrough and a flange portion at one
end thereof within said bore of said chain guide member such that an
underside surface of said flange portion rests on a second outer surface
of said chain guide member;
radially preloading said first and second resilient members by engaging a
rigid, substantially cylindrical sleeve in an interference fit within said
bores of said first and said second resilient members; and,
fastening said chain guide member to said engine by passing a fastener
through said sleeve and said bores.
16. A method according to claim 15 further comprising the steps of:
forming said sleeve member with a flanged portion at one end thereof for
bearing against the engine;
forming said first resilient member with an annular recess about said bore
at said flange portion end for receiving said flange portion of said
sleeve.
17. A method according to claim 15 wherein said forming step comprises the
steps of:
forming an elongate chain guide member;
forming a first bore in a first end of said chain guide member for
receiving a first vibration isolation means; and,
forming a second bore in a second end of said chain guide member opposite
said first end for receiving a second vibration isolation means.
18. A method according to claim 15 further comprising the steps of forming
an annular recess in each underside surface of said flange portions of
said first and said second resilient members near a boundary between said
flange portions and said exterior walls.
19. A method according to claim 15 further comprising the step of axially
preloading said first and second resilient members.
Description
FIELD OF THE INVENTION
The present invention relates to a chain guide mounting assembly for a
chain driven overhead cam internal combustion engine, and more
particularly to, an assembly which reduces propagation of chain related
noise throughout the engine.
BACKGROUND OF THE INVENTION
Automotive engineers have placed continued emphasis on the reduction of
vehicle noise, vibration and harshness (NVH) to ensure a smooth vehicle
operation. The inventors of the present invention have recognized a
critical area for the reduction of NVH in an internal combustion engine.
In a chain driven overhead cam internal combustion engine, a chain guide
assembly is typically rigidly mounted to the engine by a fastener, such as
a bolt, to guide the chain through its course at the front-end of the
engine. As the chain moves, chain induced vibration is transmitted through
the chain guide assembly resulting in undesirable noise. Until now, there
was no known assembly which effectively reduced chain related noise while
maintaining limited chain guide deflection.
SUMMARY OF THE INVENTION
An object of the invention is to reduce chain related noise and vibration
in a chain driven overhead cam internal combustion engine, while
maintaining limited chain guide deflection.
The above object is achieved, and problems of prior art approaches
overcome, by providing a novel chain guide mounting assembly for a chain
driven overhead cam internal combustion engine. In one particular aspect
of the invention, the chain guide mounting assembly includes a chain guide
member fastened to the engine by vibration isolation means. The chain
guide member has a chain guide surface for guiding the chain and is formed
with a bore. A vibration isolation means is provided that includes first
and second, substantially cylindrical resilient members. Each of the first
and second resilient members have an exterior side wall, an axial bore
therethrough, and a flanged portion at one end thereof. The members are
fitted within the bore of the chain guide member such that an underside
surface of each flange portion rests on opposite, outer surfaces of the
chain guide member. A rigid, substantially cylindrical sleeve is fitted in
interference engagement within the bores of both the first and second
resilient members such that a radial preload is applied thereto. A
fastener, passing through the sleeve and the bores, fastens the chain
guide member to the engine such that an axial preload is applied to both
the first and second resilient members.
An advantage of the above aspect of the invention is that chain related
noise and vibration is reduced by a chain guide assembly having vibration
isolation means.
Another advantage of the above aspect of the invention is that chain guide
deflection is minimized, thereby reducing chain speed variation and the
resulting stress on the chain guides, as well as maintaining consistent
engine timing.
Yet another advantage of the above aspect of the invention is that a wide
range of vibration frequencies are isolated.
Other objects, features and advantages of the present invention will be
readily appreciated by the reader of this specification.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example, with reference to
the accompanying drawings in which:
FIG. 1 is a diagrammatic plan view of a chain driven overhead cam internal
combustion engine according to the present invention;
FIG. 2 is a diagrammatic exploded view of the chain guide mounting assembly
according to the present invention;
FIG. 3 is an enlarged view of a portion of the chain guide mounting
assembly encircled by line 3 of FIG. 1;
FIG. 4 is a cross-sectional view of the chain guide mounting assembly taken
along line 4--4 of FIG. 3;
FIG. 5 is an exploded cross-sectional view of the chain guide mounting
assembly of FIG. 4;
FIG. 5a is a cross-sectional view of a portion of the chain guide mounting
assembly of FIG. 5 prior to assembly to the engine; and,
FIG. 6 is an enlarged view a portion of a first resilient member, according
to the present invention, encircled by line 6 of FIG. 5.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
As shown in FIGS. 1 and 2, chain guide mounting assembly generally shown at
10 is mounted to internal combustion engine 12. In the example shown
herein, two chain guide mounting assemblies are shown for a V-block
internal combustion engine, one for each bank of cylinders. Those skilled
in the art will recognize that the present invention may be applied to an
in-line engine as well. Internal combustion engine 12 has crankshaft 14,
overhead camshafts 16 and chain 18 connecting crankshaft 14 to overhead
camshafts 16. As is known to one of ordinary skill in the art, crankshaft
14 and camshafts 16 each have a sprocket wheel attached to one end thereof
so that chain 18 may transmit power from rotating crankshaft 14 to
camshaft 16.
Chain guide mounting assembly 10 includes chain guide member 20 fastened to
internal combustion engine 12. Chain guide member 20 is fastened to engine
12 by vibration isolation means 22, two of which are shown for each chain
guide member 20 in this example. Chain guide member 20 further includes
chain guide surface 24, which guides chain 18 along its path from
crankshaft 14 to camshaft 16. Chain guide surface 24 typically includes
elongate resilient member 26 mounted thereon to provide a smooth,
substantially resistance-free, chain guide surface. In a preferred
embodiment, elongate resilient member 26 is made of a thermally and
environmentally stable material such as polyaryl-ether-ether-ketone
(PEEK).
In order to apply tension on chain 18, a chain tensioning device is
provided. In the example disclosed herein, the chain tensioning device
includes chain tensioning member 28, which is a substantially elongate
member having first end 30 pivotally mounted to engine 12, and force
application means 37. Force application means 37 acts on second end 35 of
chain tensioning member 28. In this example, force application means 37 is
a hydraulically operated piston for applying a force at second end 35 so
that chain tensioning member 28 pivots about first end 30. Thus, a lateral
force is placed upon chain 18 so as to reduce slack therein.
Alternatively, those skilled in the art will appreciate in view of this
disclosure that a spring-loaded cylindrical chain tensioning device may be
used, which serves the same purpose of reducing slack in chain 18. Chain
support surface 32, which may also include elongate resilient member 34
made of PEEK, provides a smooth, substantially resistance-free, surface on
which chain 18 rides.
In prior art devices, as chain 18 would rotate or move between crankshaft
14 and camshaft 16, any vibration generated therein would be transmitted
through chain guide member 20 and then through the remainder of engine 12,
thereby increasing undesirable noise. According to the present invention,
vibration isolation means 22 is provided to mount chain guide member 20 to
engine 12, thereby reducing the amount of undesirable noise. FIG. 3
represents an enlarged view of a portion of chain guide mounting assembly
10, encircled by line 3 of FIG. 1, showing one vibration isolation means
22. As previously noted, two vibration isolation means 22 are provided to
mount each chain guide member 20 to engine 12. For the sake of clarity,
however, only one vibration isolation means 22 is shown and described
hereinafter.
According to the present invention, as best shown in FIGS. 4 and 5,
vibration isolation means 22 includes first resilient member 36 fitted
within bore 38 of chain guide member 20. First resilient member 36 is
substantially cylindrical and has exterior side wall axial bore 42
therethrough and flange portion 44 at one end thereof. First resilient
member 36 is fitted within bore 38 such that underside surface 46 of
flange portion 44 rests on outer surface 48 of chain guide member 20.
Vibration isolation means 22 also includes second resilient member 50
fitted within bore 38. Second resilient member 50 is also substantially
cylindrical and has exterior side wall 52, axial bore 54 extending
therethrough, and flange portion 56 at one end thereof. Second resilient
member 50 is fitted within bore 38 such that underside surface 58 of
flange portion 56 rests on outer surface 60 of chain guide member 20. In a
preferred embodiment, first 36 and second 50 resilient members are made of
an elastomeric material, preferably comprising fluorinated hydrocarbon or
fluorosilicone.
As shown in FIG. 4, a lateral force, represented by arrow 62, is exerted by
chain 18 onto chain guide member 20 due to the action of the chain
tensioning device. As a result, vibration isolation means 22 may move in a
lateral direction relative to axis 63 of vibration isolation means 22. In
order to prevent an undesirable amount of movement, while maintaining
vibration isolation, vibration isolation means 22 of the present invention
includes rigid sleeve 64, such as a steel sleeve, in interference
engagement within bores 42 and 54 of first resilient member 36 and second
resilient member 50, respectively. The effect of the interference
engagement results in a radial preload on both first and second resilient
members 36 and 50, respectively, thereby reducing the amount of
undesirable lateral movement. It is desirable to reduce lateral movement
so as to provide the benefit of reducing speed variation of chain 18 and
the resulting stress on chain guide member 20. Further, it is desirable to
reduce lateral movement to maintain proper timing of engine 12. To
complete the assembly, washer 66 overlays top surface 67 of flange portion
56. Fastener 68, such as a bolt, passes through washer 66, sleeve 64 and
bores 42 and 54 of first resilient member 36 and second resilient member
50 and is fastened within threaded hole 70 of engine 12. To further reduce
lateral movement, an axial preload is also applied to vibration isolation
means 22. As shown in FIG. 5a, which is a cross-sectional view of a
portion of the chain guide mounting assembly of FIG. 5 prior to assembly
to the engine, rigid sleeve 64 has an axial length L.sub.s less than the
length L.sub.R of first and second resilient members 36, 50 when fitted
within bore 38. As a result, when fastener 68 (FIG. 5) is tightened, first
and second resilient members 36, 50 compress in an axial direction,
thereby providing the axial preload.
In a preferred embodiment, sleeve 64 has flange portion 72 at one end
thereof to provide a greater bearing surface on engine 12. Engine 12 may
be made of aluminum and thus flange portion 72 decreases the resulting
bearing stress to reduce the likelihood of damage to engine 12. To
accommodate flange portion 72, first resilient member 36 has annular
recess 74 located about bore 42, as best shown in FIG. 6. In the example
shown herein, flange portion 72 of sleeve 64 and annular recess 74 of
first resilient member 36 each form a frusto-conical surface thereby
providing a maximum amount of force distribution between sleeve 64 and
first resilient member 36.
As fastening means 68 is tightened so as to compress first resilient member
36 and second resilient member 50, an area of concentrated stress rises in
the location generally shown at 76 of FIG. 6. To reduce the likelihood of
a tear in that area, both first resilient member 36 and second resilient
member 50 are each provided with annular recess 78 in underside surfaces
46 and 58, respectively. FIG. 6 shows recess 78 in first resilient member
36 only. Annular recess 78 is located near the boundary between flange
portion 44 and side wall 40. Similarly, second resilient member 50
includes annular recess 78 in underside surface 58 of flange 56 near a
boundary between flange 56 and side wall 52.
While the best mode in carrying out the invention has been described in
detail, those having ordinary skill in the art in which this invention
relates will recognize various alternative designs and embodiments,
including those mentioned above, in practicing the invention that have
been defined by the following claims.
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